1. Field of the Invention
The invention relates to a tapered roller bearing.
2. Description of the Related Art
Tapered roller bearings can receive a radial load and an axial load in one direction and are used in various fields. For example, a tapered roller bearing is used to support a shaft provided in a gear mechanism for a transmission, a differential apparatus, and the like in an automobile. Such a tapered roller bearing includes an outer ring, an inner ring, a plurality of tapered rollers, and an annular cage. The outer ring has an outer-ring raceway surface that increases in diameter from a first side toward a second side in an axial direction. The inner ring has an inner-ring raceway surface facing the outer-ring raceway surface and has a cone back face rib (large rib) on the second side of the inner-ring raceway surface in the axial direction. The tapered rollers are interposed between the outer-ring raceway surface and the inner-ring raceway surface. The cage holds the tapered rollers spaced at intervals in a circumferential direction.
For example, in the differential apparatus, a bottom portion of a housing of the apparatus serves as a lubricant reservoir (oil reservoir). A rotating ring gear scoops up and splatters a lubricant stored in the lubricant reservoir to allow the lubricant to be used to lubricate the tapered roller bearing. However, in an initial stage of rotation such as starting of an engine, feeding of oil to the tapered roller bearing based on the scooping up of the lubricant as described above is insufficient. Thus, the tapered roller bearing may be in a poor lubrication state. In the tapered roller bearing, large end faces of the tapered rollers come into sliding contact with the large rib of the inner ring. Consequently, when these sliding contact portions are in the poor lubrication state, temperature may be elevated due to sliding friction, leading to seizure.
Thus, a tapered roller bearing has been proposed in which a ring member (partition plate) with an L-shaped section is attached to a part of the outer ring that corresponds to an outer position of the large rib of the inner ring in a radial direction, that is, to an end of the outer ring (see FIG. 5 and FIG. 6 in Japanese Patent Application Publication No. 2008-57791 (JP 2008-57791 A)). The ring member allows the lubricant to be stored in the tapered roller bearing. Consequently, in the initial stage of rotation, the lubricant can be utilized for lubrication between the large rib of the inner ring and end surfaces of the tapered roller bearings.
The tapered roller bearing described in JP 2008-57791 A, the lubricant stored in the ring member with the L-shaped section allows enhancement of the resistance to seizure between the large rib and the tapered rollers. However, the lubricant contains foreign matter such as wear debris, and thus, such foreign matter is stored in the tapered roller bearing by the ring member with the L-shaped section. When the foreign matter reaches between the large rib and the tapered rollers or a bearing interior where the raceway surfaces for the tapered rollers and the like are located, the life of the bearing is shortened.